I'd respectfully disagree with that statement. UTM's should never be truncated, that model is found in MGRS and USNG to describe areas. The only truncation that I've seen on UTM's, and I still don't agree with, is dropping the zone designation from the Easting. I don't know of any regional SAR team that would train or operate that way. I also don't agree with rounding. Why would you do that? What benefit does it give you by intentionally making your coordinates less accurate?johngo wrote:When I first learned UTM coordinates, I was taught to round off. This just intuitively made sense to me as it would seemingly give you a more accurate position. Then, in researching it further, I read from a couple of fairly reputable sources that you should not round off, but rather truncate. Initially that did not seem to make much sense to me, but I thought OK, I'm hearing it from a SAR team manual, that must be right. So now I teach truncating. Perhaps I will go back to rounding, is ultimately it probably doesn't make much difference.
No formal roamers. They're not worth much, and aren't very versatile, I train my people to make a roamer as needed, generally just using the corner of a piece of paper (or the same map) and the graphical scale. (another reason I'm not a huge fan of CalTopos printed maps). A 50m window on a 1:24,000 isn't all that difficult to achieve. Maps aren't always printed at the same scale, photo copies of maps can distort them more. I'd rather give my people the ability to make a reader for any map they're using, and think critically about the methods being used.johngo wrote: 25 m accuracy in plotting coordinates is pretty impressive. I am assuming you are using a map romer, or some sort of plotting tool? While some professional users, such as SAR teams, foresters, archaeologists, wildland firefighters, etc. might need that level of precision, I feel that most civilians are going to be fine with about 100 m. For example, ff you need to tell 911 where to send the search party that should be more than sufficient.
25 m accuracy usually requires some additional plotting tools, and in my experience cannot really be done on a standard scale map around 1:25,000 on 8.5 x 11 paper by eyeball alone. I do not encourage most casual users to carry things like a map romer, because they are small, somewhat fragile, and easily lost.
Side note, 911 doesn't work in UTM's. I'm not sure who told you that bit. Dispatch, cell pings, virtually all modern technology runs in D.ddd° Lat/Long in WGS84 by default. SAR teams use UTM's due to various pro's and the user friendliness. If you try to give a 911 calltaker UTM's they're going to be extremely confused. From a SAR perspective, it shouldn't matter what format you give coordinates in, they should be able to convert and plot as needed.
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